Lubricant and process for preparing the same



, fled method of preparing the desired compounded PatentedMar. 20, 1945Arthur Lazar, Concord, Paul Moritz Buedrich,

Berkeley, and Raymond Le Roy Frazier, Concord, Calif., assignors toAssociated Oil Company, a corporation of California, Tide ,WaterAssociated Oil Company, a corporation of Delaware No Drawing.sApplication January 5, 1937, 3

erial No. 119,158 13 Claims. (01. 252+) This invention relates toimprovements in lubricants and has for a principal object the provisionof a compounded hydrocarbon lubrieating oil of highly improved oilinesscharacteristics. I

Another object of the invention is to provide a lubricating oil havingpronounced non-sludgin characteristics.

Another object of the invention is to provide a lubricating oil ofsumciently high stability to m prevent the formation of gummy andresinous oxidation and polymerization products. Another object is toprovide a novel and simpli lubricating oil.

Further objects will become apparent as the invention hereinafterbecomes more fully disclosed.

Lubricating oils for use in engines, particularly internal combustionengines, must have certain properties which tend to assure longcontinued operation of the engineby providing complete lubrication ofthe parts thereof, especially the cylinders,- pistons and piston ringswhich are subject to severe heat conditions.

TLG above is particularly true of lubricating oils manufacturedspecifially for use in internal combustion engines of the Diesel t e inwhich higher compression pressures and higher airfuel ratios areessential operating factors.

To maintain such high compression for efliciency reasons the pistonrings must fuction perfectly without sticking under the concomitant heatconditions to which the piston and piston rings are subject.

Also the above facts are true when applied to any type of internalcombustion engine other than the'Diesel type, even though in theordinary spark ignition type of engine operating under relatively lowercompression pressures than 0 the Diesel type, the operating temperaturerange of the pistons and piston rings of said spark ignition type may behigher than that of similar parts of the Diesel type.

This is particularly true of the high speed Diesel type of engineequipped with aluminum pistons on account of the better heatconductivity of aluminum when compared to iron. However the object ofthe invention is to design a compounded lubricating oil which will showthe desired stability towards oxidation and polymerization over a widerange of heat and pressure conditions in order to fit into the serviceof any kind'of internal combustion engine, as partially illustrated by,

(1) Engines operating on spark ignition of compressed gaseous fuels (gasengines) (2)-Engines operating on spark ignition of vaporized liquidfuels (gasoline engines) (3) Engines operating with compression ignitionof atomized heavy liquid fuels (Diesel engines).

In all these services it is essential that the lubricant has goodaflinity for metal surfaces,

which is maintained at the conditions prevailing on those surraces undera wide range of temperatures and pressures;

In order to more fully comprehend the scope of the invention, it shouldbe understood that mineral oils suitable for lubricating oils consist ofa mixture of different series of hydrocarbons.

Depending on the origin of the crude oil, such mixture may include thesaturated, the unsaturated, and the aromatic series of hydrocarbons,which are thus above defined for the purposes of the invention and anyboning range of Iimsned lubricating oil may include one or more of theabove series.

Heretofore in refining lubricating crude oil, it has been consideredadvisable to so treat the oil that most of the unsaturates and aromatichydrocarbons will be removed and leave only a body of substantiallysaturated hydrocarbons for use as a lubricating oil. However suchsaturated oils are not only deficient in him strength or oiliness, andadherence to metal surfaces, but upon exposure to air at hightemperature and high pressures, oxidation occurs in the cylinders of anengine, whereby acidic compounds are formed which is considered theinitial step in their deterioration as lubricating oils.

Such oxidation products are of a resinous, oil insoluble, type whichgather around the piston rings inthe ring grooves and cause piston ringsticking and thus the ultimate seizure and scor ing of the piston in thecylinder.

Inasmuch as oxidation in general is largely.

a function of temperature, there is a certain temperature range withinwhich saturated hydrocarbons might function well as lubricating oil ininternal combustion engines without deteriorabe treated as herein setforth. The processin of the basic' oil may be by well known methods,such as by selective solvents like liquid sulphur dioxide, phenol,dichlorethylether, furfural, nitrobenzene and the like, or by sulphuricacid, or by both, to'any desired degree of refinement.

In the removal of the undesirable constituents of the oil by the abovementioned methods it may be desirableto retain inthe oil certaincompounds of acidic nature, as originally present in raw lubricating oildistillates. Reference is specifically made to the so-called naphthenicacids, which by proper application of the treating methods may be leftin the refined lubricating. oil. This will be further illustrated in thefollowing description of the process herein disclosed.

There are two methods by which the invention may be practiced. In thefirst method a raw, lubricating oil distillate containing organic acidsnormally present in such oil, such as naphthenic acids, is treated in ausual manner preferably with a selective solvent of the type liquidsulphur dioxide, phenol, dichlorethylether, furfural, ni-

trobenzene, or the like to yield a raffinate comprising substantiallythose hydrocarbons which have the desired characteristics of alubricating oil. To such treated oil is added suflicient metal oxide orhydroxide; preferably calcium oxide or hydroxide, to form ametal soapin, the oil; such soap comprising about between 0.01% and 1.0% by weightof the oil. The oxides or hydroxides are preferably selected from thegroup of the soap may be accomplished by adding instead of calcium oxideor hydroxide, the free calcium metal or even a suitable calcium salt,such as calcium acetate, in which the acetic acid radical can be easilydisplaced by that of the less volatile higher molecular weight organicacids.

Alternatively, where the organic acid content of the lubricating oil isinsufilcient to provide a alkaline earth and earth metals, namely,calcium,

strontium, barium, magnesium, zinc, aluminum, chromium. Most preferredof those enumerated is calcium oxide or hydroxide, not only by reason ofeconomygibut also particularly because the calcium soaps are mosteffective for the purpose of imparting resistance to oxidation andnon-sludging characteristics to the oil, but the invention is notlimited thereto.

Alternatively the conversion of the free organic acid to a metal soap,more specifically a calcium desired percentage of incorporated soap asabove described, suflicient organic acids may be added to the oil priorto saponification to obtain the required soap content, or a desiredpre-formed metal soap may be added to an oil lacking in organic, acidityin the desired proportions.

Again, in the event that the treated lubricating oil is lacking incontained organic acids, such acids may be added in the form of fattyacids together with equivalent portions of metal base to form the metalsoaps.

In general, the higher molecular weight fatty acids are to be preferredwhere their calcium soaps areito be used and the type fatty acid to beused may include saturated or unsaturated, hydroxy, or. polybasic fattyacids, or mixtures of the same. Carboxylic acids derived from cyclicnuclei in general are not particularly suitable for our purposes,primarily on account of their very low solubility but also on account ofthe relative instability of their metal soaps.

However, aryl-substituted fatty acids of the type CnH2n2(Ar) COOH,resemble in their solubility and stability the ordinary fatty acids andtherefore may be used in form of their alkaline earth metal soaps.

As examples of different organic acids, which I have been tried, thefollowing tabulation may be presented, showing the solubilitycharacteristics, the stability of the compounded oil and the sludgeinhibiting characteristics of each particular soap. The sludging testwas carried out by heating a 100 gram sample of the oil, containing 1%by weight of the particular soap, to 330 F., for 24 hours in presence ofa metallic catalyst, which contains all the metallic elements present inthe oil circulation system of an internal combustion engine (iron,copper, lead) which are also known as accelerators for oxidation.

The color of the original oil before heating and the addition of thesoap, was between 10 and 20 TABLE No. 1

. Characteristics of compounded oil after heat test Solubiliity oi seepsMetal soap added to mineral lubricating oil g Thm tures Appearance 54,"cell Lovibond None Slight carbonaceous deposit 550 Calcium soup: ofsaturated acids Melissic acid, 030E500: Slight Slight ppte. of soap 4oMontsnic acid, CflHleOi ..do ..do 45 Cerotic acid, CzaHnO: 5o Lignocericacid, CuHuOz- Beliemic acid, CaHHOL- Aracbidic acid, 0 11400. 110Stearic acid, 0 911" 1.... 130 Palmitic acid, CldH32OI-- 180 Myristicacid, 0141111102.. 240 Laurie acid, 0 2151401 300 Capric acid, CmHillOI-400 Butyric acid, C4Hs0:-- Opaque Acetic acid, CzH Opaque Calcium snapsof unsaturated acids Erucic acid, Cannon-.- Moderate lear 110 Oleicacid, CnHuOa High Slight ppte of soap. Elaidic acid, CisHu I. -....d0Trace oi soap 60 Linoleic acid, CnHuO: ..do Heavy ppte. of soapTeliairlc acid, curb-o- Y do do Llnolenic acid, fin 200 Chancteristim ofcom unded oil after h Solubility olsoeps m Metal soap added to minerallubricating oil Thm color a tum A pearance cell Lovibond Calcium soapsof saturated hydroau acids r Mono-hydroxy stea'riq acid, lBHll02(0H)-Moderate... Clear u. 12o Di-hydroxy stearic acid, CuHuOdOH): do ...do130 Tri-hydroxy stearic acid, CnHnOflOHh. Trace of soap.. 7Tctra-hydroxy stearic acid, CuHuOKQHM. do. o 2m Hexmhydroxy stearicacid, C1sHw0:(0H)| Very slight Slight ppte. of soap., 260

' Calcium snaps of unsaturated hydrozy acids Ricinoleic acid, C1aHsa 2(High Gummy ppte 200 Calcium soup: of chlorinated acids i Chlorinatedstearic scid...-.' Moderate Clear Chlorinated oleic acid "r Hig "do 150Calcium soups of cyclic acids Benzoic acid, CaHsCOOH Salicylic acid,C6H4(0H)COOH- Cinnamic acid, aH| H= H 0H..... 550 Hydrocinnamic acid,CflHlCHzCHflCOOH 550 Phthalic acid, CoH|(CO0H)2 c 550 Naphthoic acid,CmHvCOOH 550 Abietic acid, CnHznCO0H Naphthenic acid (extracted irompetroleum) 55 Slight ppte. of soap -1'50 1 Cle 130 Strontium'naphtheuate. 30 Barium stearato l 150 Barium oleate 110 Bariumricinoleate. 220 Barium abietate Barium naphthenate. Aluminum stearateClear Aluminum oleate. Slight ppte. of soap. 350 Aluminum abietate Heavyppte. of A110 400 Aluminum naphthenate Clear 150 Zinc steerato .dc. Zincoleate. do 200 Zinc abietate g l .d0 250 Zinc naphthenate.. Slight ppte.of ZnO 400 Chromium oleate Heavyppte. oi ch03. 220 Chromium naphthenate-.d0 ..do 250 I Up to 0.1% by weight, 9 Up to 0.5% by weight. 3 Morethan 0.5% by. weight.

in a Lovibond cell. A darkening of the colorv is therefore indicated bythrough color substany y 5 treated or untreated, have a higher solvencytially above 20.

In this mode of operation the formation of the soaps involves theformation of molecular equivalents of water by reaction. This water hasto be removed from the system because it interieres with the homogeneityof the soap-oil-mixture. To this end, during the formation or addi-* isfound that the solubility of most of the soaps in the oil requiringstabilization is definitely limited and is in the lower brackets of: theabove percentages. Such solubility varies inversely with thecarbon-hydrogenratio f the oil, or with the degree of saturation of theoil. In consequence, the solubility of the alkaline earth metal soapsmay be sufficient to retain the soapin a certain oil withoutprecipitation up to a relatively high percentage while, on the otherhand, certain, other desired hydrocarbon oilswill precipitate out aportion of the stabilizing soaps desired to be retained.

As an instance of this, lubricating oils derived from asphalt ornaphthene base crudes, whether treated lubricating oil distillate has ahigher solvency power for these soaps than one which had been treatedwith either selective solventsor sulphuric acid.

The second method of treatment herein comprehends the incorporation andretention of alkaline earth metal soaps in a lubricating oil regardlessof the origin or degree of refinementof the oil.

An increase in the solubility of alkaline earth metal soap andpermanency of its solution in an oil maybe accomplished by subjectingthe mixture during formation of the soap or after the addition thereofto a temperature of at least about 400 F., for a period of timesufiicient to drive off all water formed by the saponification. However,

with this heat treatment of certain oils, undesirable darkening willoccur, and thereforeit is preferred to use an agent which has adispersing and homogenizing effect on the soap at lower temperature tomake the same completely and permanently soluble in the oil andfurtherto effect (A) Agents which are of a boiling range lower than thatof the oil andwhich are removed from the oil after having exercisedtheir dispersing function.

(B) Agents which are of a boiling range not necessarily lower than thatof the oil which will remain in the oil to serve as homogenizers for'the compounded oil.

.such compounds foundsultable, are compiled in Table No. 2 (Dispersingagents).

TABLE N0. 2 v

Group ADispe1'sing ag nts Dispersing Material used action upon soap Amy}L 1 Poor. Octyl alcohol- Fair. Lauryl alcohoL Good. Benzyl elmhnl Do.Ethylene glycol. Diethylene glycoL. Phen (from! Hexahydrophenol. Good.Amyl ether Poor. Methyl ether oi: ethylene glycol... Good. Methyl etherdiethylene glycol--. Fair. Methyl phenyl ether Benzyl ether Do. Butyricacid Poor. Laurie acid.. Good. Nephthenic acid Do. Am lnnafnfn POOLCellosolve acetate Do. Dimethyl phthalatego. 0. Fair. Good. Poor. 7

D0. Fair. Citral Good. Benzaldehyd Do. Aniline. Poor. Pyridine Do.Dichlorethyl ether--. Do. 'letrachlorethane Do. Chlc m Good.Chlornaphthalene Do. Petroleum naphtha Poor. Coal tar dis Do. Methylngphfhnlnnl F in Tetrahydr -f D0.

. Of these listed the methyl ether of monoethylene glycol isparticularly useful in the process.

This solvent has a boiling pointof 285 F., and

,metal soap, such as calcium oleate for instance,

which has been made from hydrated lime 'and oleic acid, and the waterformed therefrom is tenaciously retained, is mixed with the describedperformed while under agitation with an inert gas, such as carbondioxide, nitrogen or the like, which prevents darkening of the oil, andthe mixture may thereafter be heated to a temperature corresponding tothe boilingi point of the solvent, in the presence of the inert gas, or'8. temperature sufiieient to drive off all the solvent and all thewater but insuflicient to distil the oil. I

Experiments confirm the fact that the desired dispersing agents of thetype class A should exercise the double function of dehydrating the soapwhile being soluble in the oil and by the mechanics of these functionsit may readily be seen that .an anhydrousv soap is easily dispersedthroughout the anhydrous oil to stay in permanent solution therein;

In order to render the solution of soap in oil permanent, it ispreferred to subject the mixture to a prolonged heat treatment after thesolvent (and water) has been driven off. Ordinarily there is a tendencyfor some of the soap to form a precipitate-if suddenly chilled, orreduced in temperature immediately after removal of the water andatemperature of about 150 F., andabove is maintainedon the mixture for aperiod of about '24 hours, a clear solution will result whichwill remainclear indefinitely.

In this respect, it is preferable to so. mix the soap and solvent with asmall portion of the hydrocarbon oil and to make a soap stockconcentrate and then at a later period, when convenient, to distributethe same in larger amounts of oil to bring the percentage of soap in thefinal product within the stated limits. This will be better appreciatedwhen it isknown that the ether, water of reaction is abstracted from thesoap by the ether and thereby permits the complete solution of the soapin the oil. 7

The mixing of soap and oil is preferably be illustrative.

solubility of calcium oleate a California motor oil of S. A. E. 30 gradeat room temperature is between0.1%. and 0.5% 'byweight, whereas byfollowing our specified procedure of dispersing and homogenizing asdescribed under class A, it is possible to maintain up to at least 10%of calcium oleate in solution, and hence more concentrated solutions maybe reduced by dilution to the desired percentage.

Agents 'of class B, which may be called homogenizing agents, includesuch types of compounds as the esters or ethers, or ester-ethers of highmolecular weight fatty acids such as oleic or stearic acid; of whichmethylether of ethylene glycol oleate, diglycol laurate, diglycololeate, may

Also the esters of mono or polyhydric alcohols, partially or fullyesterified, such as derivatives of amyl alcohol, glycol or glycerol, ofwhich butyloleate and amyl stearate are illustrativ'e. By this method itis possible to incorporate even higher percentages of alkaline earthsoap into any type of lubricating oil. As an example, it is possible tomake a solution of up to 30% by weight of calcium oleate in an S. A. E.30 grade motor oil, which will stay permanently clear and fluid andwhich can be blended in with more mineral oil to give a permanent clearsolution of any desired concentration between 0 and 30%. Examples ofvarious homogenizing agents 15 used are illustrated in Group Bot TableNo. 2A.

- affinity of the lubricating oil.

assures TABLE No. 2A

Group B-Homoqeni2ino agents Homogen- Material used izing action uponsoap Butyl stearate Fair. Am lstearaie. Good. D ycol steal-ate Poor.

Et yl oleatc Good.

Butyl oieate Do. Diglycoi oleate. Fair. Phenyl oleate Good. lein Do.Methyl Celiosolve oleate Do. But 1 Cellosclve stearate Fair.

Met yl ester of monochlor stearlc acid. Methyl ester of monochlor oleicDo. Chlordiphenyl i Do.

Furtheragents of class B include halogenated aromatic compounds such aschlorine substitution products of aromatic hydrocarbons and morespecifically chlorinated diphenyl. Also certain aliphatic halogencompounds may, be used advantageously as stabilizing agents for thecompounded oils, such as halogen substitution products of high molecularweight fatty acids, or their esters. As an example may be given themethylester of monochlorstearic acid.

It is interesting to know that the use of homogenizing agents as abovedescribed has an added beneficial effect upon the film strength andmetal This is particularly striking with the halogen containinginradients. v

As a special case of great interest we wish to emphasize the following,in which a metal soap, more specifically a calcium soap of a halogenatedhigh molecular fatty acid is used as an oxidation inhibitor. We havefound that metal" soaps of a great number of halogen substituted fattyacids are not only readily soluble in mineral oils, but also impart verypronounced oxidation inhibiting characteristics to those oils.

lowing table shows a comparison between a straight mineral oil and acompounded product made from the same oil by addition of a metal soap,using either dispersing agents or homog,

enizers, or by addition of metal soaps of chlorinated' fatty acids.

Teens: No. 3

Comparison of straight mineral oil with oil compounds for stabilizationViscosity s. U. Gray. Flash Fire Californialubrlcsting oils slam.-. 223no 460 so? no 58' Same, containing 1% by we lit 1 Ca oieateincorporated, us

methyicellosoive as dispersing agents V. 22.2 410 460 612 231 58 Same,containing 1% by weight oi Ca cleats-0.5% oi amylstoarateasbomogenizingt. 22.1 410 465 618132 59 Same containing 1% b we ght V of (5s soap ofmen orstearic acid 22.2 415 410 612 2&0 as

In the above disclosure a numbervof preferred methods have beenindicated for the manufacture of a compounded lubricant containing fromrelatively minute to large quantities of desired soaps. It should,however, be understood that this invention is not limited to the aboveexamples, and it is possible to also manufacture compounded lubricantsby a combination of these steps, and particularly within certain rangesof solubility, by the manufacture of a soap dissolved in a dispersing orhomogenizing agent and the utilization of this mixture in compoundingthe oil. Thescope of the invention is more clearly It appears that thepresence of the halogen in the fatty acid radical takes care ofthedesirable solubility characteristics as well as the film strengthcharacteristics of the added ingredient, while the fatty acid radicalstill has preserved its oxidation inhibiting quality.

Metal soaps of the following halogen substituted fatty acids have beenfound effective.

In compounding'mineral lubricating oils in the various mannersdescribed, the general physical characteristics such as gravity, flash,and fire points, and viscosity, are not materially changed so'that thedesired stability features in these lubricating oils can be obtainedwithout necessitating any changes in S. A. E. rating. The fol- We claim:

1. The process of preparing a lubricating oil having increasednon-oxidizing and non-sludging characteristics under operatingconditions in an internal combustion engine, which comprises: preventingoxidation of hydrocarbonsin. a body of petroleumlubricating oil and itsnormally con tained organic acids by adding to said body sufflcientoxide or hydroxide of a metal from the group calcium, strontium, barium,magnesium, zinc, aluminum, chromium to form a soap theredefined by thefollowing claims.

in comprising about between 0.01% and 1.0% by weight of the oil,agitating the mixture with a common solvent for the oil and soap toefiectpermanent dispersion of the soap in the oil, and

heating the mixture-to a temperature sufficient to distil oil? thesolvent with the water of reaction, but insuflicient to distil the oil.

2. In a process for preventing oxidation of pe; troleum hydrocarbon oilexposed to operating conditions of an internal combustion engine inwhich soap derived from the reaction of a high molecular weight organicacid with a metal base of the group calcium, strontium, barium, mag-inesium, zinc, aluminum, chromium is dissolved throughout a body of saidoil in the proportion of from about 0.01% to 30.0% by weight of the oilunder conditions where water is present, the steps which comprise:increasing the solubility of said soap in said oil by adding to themixture a com mon solvent for said oil and said soap and distilling oil?the water and solvent; said solvent being of an organic nature otherthan hydrocarbons and having a boiling range lower than the oil buthigher than that of water.

3. In a'process for preventing oxidation of petroleum hydrocarbon oilexposed to operating conditions of an internal combustion engine inwhich soap derived from the reaction of a high molecular weight organicacid with a metal base of the group calcium, strontium, barium,magnesium, zinc, aluminum, chromium is dissolved throughout a bodyofsaid oil in the proportion of ,from about 0.01% to 30.0% by weight ofthe oil under conditions where water is present, the steps whichcomprise: increasing the solubility of said soap in said oil by addingto the mixture a common solvent for said oil and said soap anddistilling ofi the water and solvent; then maintainthe mixture a commonsolvent for the oil and the soap, and distilling ofl the water ofreaction and the solvent.

ingthe mixture under a temperature of about 150 F. for a period of about24 hours.

4. A lubricating oil for internal combustion en-v venting the stickingof the piston rings of internal combustion engines at high temperaturesand pressures.

5. The process of preparing a stable lubricating oil which comprises:dispersing throughout a body of liquid hydrocarbon lubricating oil from0.01%

s to 30% of a soap derived from the reaction of a high molecular weightorganic acid with a metal base of the group calcium, strontium, barium.magnesium, zinc, aluminum, chromium, while in the continued presenceof aagent other than hydrocarbons sufiicient to maintain such dispersion andsuflicient to maintain the mixture liquid at normal room temperaturewhen the dispersing agent is removed, then removing the dispersing agentby distillation.

6. The process of preparing lubricating oils which comprises: treating ahydrocarbon lubricating distillate and its normally contained organicacids with a selective solvent and removing the solvent, adding to theoil still containing acids sufiicient oxide or hydroxide of a metal fromthe group calcium, strontium, barium, magnesium, zinc, aluminum,chromium, to neutralize said acids and form a soap therein comprisingbetween 0.01% and 1.0% by weight of the oil, adding to not less than tencarbon atoms to the moleculev '1. The process of increasing thestability'of lubricating oil so as to lessen or avoid piston ringsticking, which comprises dispersing from .0i%

to 30% by weight'of an oxidation inhibiting soap inthe oil by action ofa common solvent for the soap and oil, and then heating the mixture todistill off the solvent and any water that might be present, le'avingthe soap permanently dispersed in anhydrous'oil.

8.- The process of claim 7 followed by maintaining the oil for about 24hours at a temperature above about 150 F.

9. The process of claim '7 in which the soapv is the reaction product ofan organic acid having with a metal base of the group calcium, stron-.tium, barium, magnesium, zinc, aluminum, chromium.

10. Ardehydrated soap concentrate comprising -mineral lubricating oilcontaining oil-soluble-calcium soap of chlorinated fatty acids having atleast ten carbon atoms to the molecule and containing chlorinerepresentative of a preponderance of dichloro acids, the compositionbeing substantially free from calcium chloride.

11. A lubricating oil, which is normally freely liquid comprisingmineral lubricating oil and at least about one per cent of calciumchloro fatty I acid soap containing chlorine corresponding generallywith the dichloro soap, the soap being almost completely anhydrous andfreely soluble in the oil without imparting substantial viscosityincrease or grease-like characteristics to the original lubricating oil.

12. A lubricating oil according to claim 1l wherein the mineral oil is anaphthenic base oil.

13. A normally liquid Diesel engine lubricatin oil comprising a viscousmineral lubricating oil containing a small percentage of a freelyoilsoluble calcium soap of an organic acid having at least about tencarbon atoms per molecule with a film-strength-increasing agentconsisting of'chlorine, the soap being present in amount sufficient toovercome substantially deposit of gummy and varnish-like materials inDiesel engine: without producing appreciable viscosity inc'reasr in theoriginal oil and without imparting grease like characteristics.

ARTHUR LAZAR. PAUL MORITZ RUEDRICH. RAYMOND LE ROY FRAZIER.

